Suggestions for first upgrade

I recently discovered what a big difference good headphones make when I listened to some music on my friend's Grado SR-60s. I decided it's time for an upgrade from the Sennheiser mx400 that came with my iRiver (which I run with Rockbox for FLAC). What I liked about the SR-60 was the sound. I don't quite know how to describe it, but my friend said they have a "fun" sound. However, the SR-60's let out and in quite a bit of noise, and I will be using these as I walk to my office, as well as in the office. Also, I found that I had to turn the volume up higher than I normally do to get what I wanted out of them. I have a strict $100 budget, so a headphone amp is probably not in the cards. I need something that will give me distinctly better sound than my mx400, with some isolation (more the better I suppose) and that won't eat up my battery too fast. I am OK with almost any style: closed, canal, IEM, clipon etc. I listen to a lot of instrumental rock, like The ****ing Champs, and some IDM like Venetian Snares, not much vocals in any of my music. I would like to be able to hear some detail and power out of the guitars. Some models I've looked at include AKG K 26 P, PX100, super.fi 3, HD 280 pro, ep630. Thanks for helping me out!

I'm not into these IEM thingies, but as closed portable "serious" fon under 100$ I'd recommend the AKG K81/K518. Definetely on the "fun" side of things. You gotta like nutty bass though, but as is generally known, the reception of bass on the go differs significantly from cultivated home listening.

You can grab the Westone UM1s for $109.00 on earphonesolutions.com. As far as I can tell... that is a sweet deal. I never had the UM1s but I did have the UM2s. The comfort and sound quality is unparalleled. You can do some research on here for reviews on the Westone UM1s (there are appreciation threads and whatnot). That gets my vote as far as an IEM choice.

It's too bad that you need the isolation, because Grado's are absolutely perfect for the genre's you listen to. However, I found that the ER-6i's are comparable to the SR-60's in nearly every aspect except bass, which the Grado's excel at. They're definitly worth a look if you want an IEM.